Make an image behind an image be clickable

I’m hoping that there’s a way to make an image that is stacked underneath another image be clickable while the front image is not.

The front image is a semi-transparent png (think of a watermark or similar). The image behind is linked to an action. (This is not exactly what it does, so please no off-topic comments about this being a poor way to watermark… I know that!)

However if the image is in front the action will not ever be triggered, as the front image is ‘blocking’ the click.